On Fri, Oct 11, 2019 at 06:59:00AM +0000, Andreas Rheinhardt wrote:
> Limin Wang:
> > On Fri, Oct 11, 2019 at 06:20:00AM +0000, Andreas Rheinhardt wrote:
> >> lance.lmw...@gmail.com:
> >>> From: Limin Wang <lance.lmw...@gmail.com>
> >>>
> >>> Signed-off-by: Limin Wang <lance.lmw...@gmail.com>
> >>> ---
> >>> libavfilter/vf_random.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/libavfilter/vf_random.c b/libavfilter/vf_random.c
> >>> index 1937eae771..9f2153be61 100644
> >>> --- a/libavfilter/vf_random.c
> >>> +++ b/libavfilter/vf_random.c
> >>> @@ -33,7 +33,7 @@ typedef struct RandomContext {
> >>>
> >>> AVLFG lfg;
> >>> int nb_frames;
> >>> - int64_t random_seed;
> >>> + int32_t random_seed;
> >>> int nb_frames_filled;
> >>> AVFrame *frames[MAX_FRAMES];
> >>> int64_t pts[MAX_FRAMES];
> >>>
> >> { "seed", "set the seed", OFFSET(random_seed),
> >> AV_OPT_TYPE_INT64, {.i64=-1}, -1, UINT32_MAX, FLAGS },
> >>
> >> So in addition to the complete range of an uint32_t one also needs
> >> another value that instructs init to get a random seed of its own.
> >
> > yes, the max range is UINT32_MAX, so no need to use int64_t
> >
> First of all, simply changing the value to 32 bit is not right -- you
> would also have to change the type in the corresponding AVOption (it
I haven't see .i32 type for AVOption
> might seem to work on little-endian systems, but it certainly doesn't
> on big-endian systems; actually using -1 as random_seed would probably
> already not work on little-endian systems either). Second, there are
> more legal values for random_seed than values representable in 32 bit,
> hence one has to use a type with more than 32 bit.
random_seed = -1, it'll get the seed by av_get_random_seed(), it'll
return 32bit.
else
uint32_t seed
seed = s->random_seed;
av_lfg_init(&s->lfg, seed);
the seed is uint32_t still, so user can't use with more than 32bit
for the current code.
>
> - Andreas
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